• Energy Research

Using recycled rubber crumbs as drainage layer in extensive green roofs have high potential to reduce the heating and cooling loads in buildings over traditional materials used as drainage layer, such as pozzolana gravel. However, the environmental impact due to the life cycle should be analyzed to assess its environmental benefit. This paper evaluates the environmental performance of green roofs in which the drainage layer is made of rubber crumbs, a recycled material the use of which is still experimental for this purpose. In this paper Life Cycle Assessment (LCA) is applied to compare the environmental impact of four constructive systems, two extensive green roofs without insulation layer and with different drainage materials, e a recycled material, rubber crumbs, and a conventional one, pozzolana gravel -, in front of two conventional flat roofs, with and without thermal insulation (polyurethane), built in an experimental set-up consisting of four monitored house-like cubicles, located in Mediterranean continental climate (Lleida, Spain). The LCA considered the production, construction, operational, and disposal phases of the roofs, according to UNE-EN 15643-2. The operational phase was carried out using data measured in the experimental set-up, considering heating and cooling energy consumptions in the winter and summer period, respectively.

Purpose Service life of buildings is an essential parameter to evaluate its operational impact in life cycle assessment (LCA). Although most studies assume building service life about 75 to 100 years since no reliable data are available, its accurate quantification is still an unresolved work. To avoid wrong generalizations, the determination of the service life of buildings according to the characteristics of every region is required.

Abstract This review summarizes and organizes the literature on life cycle assessment (LCA), life cycle energy analysis (LCEA) and life cycle cost analysis (LCCA) studies carried out for environmental evaluation of buildings and building related industry and sector (including construction products, construction systems, buildings, and civil engineering constructions). The review shows that most LCA and LCEA are carried out in what is shown as “exemplary buildings”, that is, buildings that have been designed and constructed as low energy buildings, but there are very few studies on “traditional buildings”, that is, buildings such as those mostly found in our cities. Similarly, most studies are carried out in urban areas, while rural areas are not well represented in the literature. Finally, studies are not equally distributed around the world.

This paper presents a classification of green vertical systems for buildings. The aim of this classification is to facilitate the identification and differentiation between systems. This classification is also essential to compare future research results relating to their operation. In addition, the mechanisms by which green facades can be used as passive energy savings systems are reviewed: shadow produced by the vegetation, insulation provided by vegetation and substrate, evaporative cooling by evapotranspiration, and the barrier effect to the wind. Finally, the paper describes the first results about the behaviour of a double-skin green facade or green curtain in Dry Mediterranean Continental conditions. It is verified that a microclimate between the wall of the building and the green curtain is created, and it is characterized by slightly lower temperatures and higher relative humidity. This means that the green screen acts as a wind barrier and confirms the evapotranspiration effect of the plants. Peer Reviewed

An evaluation of the environmental impact of construction systems that are composed of facades based on alveolar bricks and macroencapsulated phase change materials done using Life Cycle Assessment (LCA) is presented. Their energy consumption rates for both heating and cooling have been measured and registered in two experimental cubicles located in Puigverd de Lleida (Spain). This work examines if the reduction of the environmental impact that is reached due to the energy savings achieved during the operational phase of these cubicles compensates the increase of the environmental impact that is induced during the manufacturing phase. Theoretical case studies, such as assuming different climatization and weather conditions, are proposed and studied to determine the most suitable climatic conditions for using the alveolar bricks and PCM technologies. Within the context of the LCA study, it is concluded that the overall benefit of PCM is the highest when summer weather conditions throughout the whole year is theoretically assumed, where for different assumed lifetime periods of the cubicles the reduction of the overall global impact of the cubicle containing PCM ranges from 12% to 14% in comparison to the other cubicle without PCM. The work was partially funded by the Spanish government (Projects ENE2008-06687-C02-01/CON and DPI2008-04099) and the European Union (COST Action COST TU0802), in collaboration with the company Hyspalit and City hall of Puigverd de Lleida. The authors would like to thank the Catalan Government for the quality accreditation given to their research group (2009 SGR 534). Lídia Rincón would like to thank the University of Lleida for her research fellowship.

Abstract In order to obtain data on the behaviour of green facades in buildings as a passive system for energy savings in dry Mediterranean Continental climate a long-term work has been performed. This paper presents the first results of two actions developed during 2009. First, the growth of four different climbing plants as well as their ability to provide shadow was studied. Second, monitoring for a year of a real green facade was carried out. The results confirmed the great capacity of green facades to produce shade, reducing the heat on the facade wall of the building. It was also verified that a microclimate between the wall of the building and the green curtain are created, characterized by slightly lower temperatures and higher relative humidity. This means that the green screen acts as a wind barrier and confirms the evapotranspiration effect of the plants. On the other hand, these results did not allow withdrawing conclusions about the insulation effect of green facades.

Today, green roofs are a building system which provides interesting benefits over traditional roof solutions. The most important advantages are the reduction of surface runoff in cities, improvement of the urban climate, biodiversity support, improvement of the durability of roofing materials, and, especially, energy savings. This paper has the aim of studying the performance of green roofs as a passive system for energy savings, within a wider objective of seeking constructive solutions suitable for sustainable and environmentally friendly architecture. This idea is tested at an experimental installation available at the University of Lleida, with several cubicles testing the energy performance of different construction solutions. This work raises the possibility of using recycled rubber from tires as a drainage layer in green roofs, substituting the porous stone materials currently used (such as expanded clay, expanded shale, pumice, and natural puzolana). This solution would reduce the consumption of these natural materials, which also require large amounts of energy in its transformation process to obtain their properties. Moreover it would provide a solution to the problem of waste rubber from the tires, known as rubber crumbs. Since the purpose of the drainage layer is the optimum balance between air and water in the green roof system, first the ability for draining of recycled rubber granules was studied and was compared with the offered by stone materials. The new solution using rubber crumbs is also studied to test if it would keep the same insulating properties that the green roof with stone materials presented in previous studies. Early results show that this extensive green roof system can be a good passive energy savings tool in Continental Mediterranean climate in summer, and that rubber crumbs can be an interesting substitute for stone materials used as drainage layer in this type of green roofs.

In this paper PCM is added to three types of stabilized rammed. Mechanical and thermal characterization is carried out. To do so, the compressive strength is optimized and the final compositions obtained are used to formulate the materials which will be thermally characterized. The optimization process is done with a design of experiments (DoE) and a variance analysis (ANOVA). Finally, LCA is used to evaluate the environmental impact during the manufacturing phase, due to the addition of stabilizers and PCM in the rammed earth. The work is partially funded by the Spanish government (ENE2008-06687-C02-01/CON, ENE2011- 28269-C03-01 and ENE2011-28269-C03-02) and the European Union (COST Action TU0802). The authors would like to thank the Catalan Government for the quality accreditation given to their research group GREA (2009 SGR 534) and research group DIOPMA (2009 SGR 645). Lídia Rincón would like to thank the University of Lleida for her research fellowship.